The Co Armagh born MP who claims Jeremy Corbyn threatened to phone his former Sinn Féin councillor father has said the Labour leader's call "would not have been well received".
Labour whip Conor McGinn, who originally hails from Camlough near Newry, said his under-pressure leader attempted to to use his family to "bully" him into silence.
Mr Corbyn is a long-standing advocate of a united Ireland and has enjoyed close relations with Sinn Féin since the 1980s.
Mr McGinn, who was elected to represent St Helens North in last year's general election, said the party leader considered using his father in an attempt to "apply pressure" on him following public criticism of Mr Corbyn. The 31-year-old MP's father, Pat McGinn, was a Sinn Féin councillor in Newry & Mourne before retiring in 2014.
His MP son has lived in Mr Corbyn's Islington constituency for more than a decade and as a long-standing Labour activist enjoyed a good relationship with the party leader.
However, relations between the two soured in May in the wake of an interview with The House magazine in which Mr McGinn suggested that Mr Corbyn needed to understand that his north London constituency – often seen as a bastion of support for radical causes like unilateral nuclear disarmament – was "not like the rest of the country".
Mr McGinn said Mr Corbyn had initially asked for his resignation and considered sacking him for the comments but he later learned that the Labour leader had threatened to call his father.
Mr Corbyn's office has dismissed the claims as "untrue" but the St Helens North MP accused the party leader of hypocrisy for talking about a "kinder, gentler politics" when "he had proposed using my family against me".
"The leader of the Labour Party was proposing to address an issue with one of his own MPs by ringing his dad," he said.
The Co Armagh-born MP said he had not made the incident public until now "because I find it shocking and embarrassing, and almost unbelievable".
In a statement, he said: "It transpired that Jeremy, in deliberations about how to respond to my interview, had said that he intended to ring my father to discuss it with him and ask him to speak to me about it.
"The leader of the Labour Party was proposing to address an issue with one of his own MPs by ringing his dad. Jeremy does not know my father so I can only presume that, because of the much-publicised fact that my father was a Sinn Féin councillor, Jeremy felt that they would share a political affinity and was proposing to use that to ask my father to apply pressure on me.
"Thankfully, others dissuaded Jeremy from taking this course of action. The call was not made, and it would not have been well-received."
Mr McGinn said he had decided to go public after watching an interview on Newsnight with Mr Corbyn in which he repeated his mantra of supporting a "kinder, gentler politics".
"I am afraid I could no longer tolerate the hypocrisy of him talking about a kinder, gentler politics when I knew for a fact that he had proposed using my family against me in an attempt to bully me into submission because he didn't like something I said."
Mr McGinn said he and other Labour MPs had been subjected to a "torrent of abuse and threats" from supporters of Mr Corbyn.
"In my constituency, a group of people gained access to my shared office building under false pretences and filmed themselves protesting outside the door of my office, in an incident that has been reported to the police," he said.
"They threatened to disrupt my surgeries and events I was attending, requiring me to have a police presence at those last weekend."
A spokesman for Mr Corbyn said: "What Conor McGinn is saying is untrue."
